Fan Control

ABSTRACT

The present disclosure relates to a hydraulic fan control circuit for a machine, in particular for a motor vehicle, a construction machine or a lifting device, with at least one hydraulic pump and at least one hydraulic motor for driving at least one fan, wherein the hydraulic motor driving torque of at least one hydraulic motor is controllable by adjusting the absorption volume.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 10 2010 031 835.3, entitled “Fan Control”, filed Jul. 22, 2010, which is hereby incorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

The present disclosure relates to a hydraulic fan control circuit for a machine, in particular for a motor vehicle, a construction machine or a lifting device, with at least one hydraulic pump and at least one hydraulic motor for driving at least one fan.

BACKGROUND AND SUMMARY

In large cooling systems for internal combustion engines keeping the cooling fluid, charge air and oil temperatures constant with variable engine load and ambient temperature is achieved by a hydraulically driven fan. The medium to be cooled flows through the fan region and is cooled to a defined temperature level by the air flow generated. For driving the fan mechanism a hydraulic motor is used, which is mechanically connected with the ventilator of the fan and is part of the hydraulic circuit.

Such hydraulic circuits consist of a hydraulic pump which sucks in hydraulic fluid from a corresponding hydraulic tank. The hydraulic fluid flows from the hydraulic pump to the hydraulic motor, in order to drive the same. The hydraulic pump generally is connected with the drive train of the machine or the vehicle and accordingly is driven by the internal combustion engine.

Within a hydraulic circuit a plurality of fan drives can be provided, to which different task areas are assigned. By the term fan drive the combination of hydraulic motor and the corresponding fan mechanism (e.g., ventilator) is to be understood. One fan drive is responsible for example for cooling the charge air of the internal combustion engine, one fan drive for cooling the cooling liquid of the internal combustion engine, and one further fan drive for cooling the hydraulic oil for the hydraulic system. Further alternative task areas are of course conceivable.

Since the required cooling capacity of the fan drives depends on certain parameters, such as the existing ambient temperature of the load present at the internal combustion engine, regulated circuits are used for controlling the fan drives for reasons of economy.

So far, every regulated fan drive has been driven with an electrically pressure-controlled variable displacement pump. Combination coolers (water and charge air coolers) are used for this purpose, which however involves the disadvantage that with rising power demand of the internal combustion engine the fan drive is turned up, in order to cool the charge air. Moreover, in the fan drive regulating circuits known so far a standstill of the fan or the fans only can be achieved by corresponding additional functions.

The object of the present invention consists in providing a circuit arrangement for a hydraulic circuit for driving a fan system which permits an independent regulation of the individual fan drives.

This object is solved by a hydraulic fan control circuit for a machine, in particular for a motor vehicle, a construction machine or a lifting device is proposed, comprising at least one hydraulic pump and at least one hydraulic motor for driving at least one fan wherein a hydraulic motor driving torque of at least one hydraulic motor is controllable by adjusting an absorption volume of the at least one hydraulic motor. The hydraulic pump preferably is connectable or connected with the drive train of the machine such that a driving force acts on the hydraulic pump. The hydraulic pump sucks in the hydraulic fluid from the connected hydraulic tank and delivers the hydraulic medium via corresponding lines to one or more hydraulic motors for driving at least one fan. The number of incorporated hydraulic motors is not limited. The present disclosure is not limited to hydraulic motors for the fan drive, but the hydraulic motors can have further alternative drive tasks.

To be able to drive the various hydraulic motors or the various fan drives independent of each other, the hydraulic motor drive torque of at least one hydraulic motor can be controlled by adjusting the corresponding absorption volume in accordance with the present disclosure. The absorption volume describes the amount of hydraulic fluid turned over by the hydraulic motor per revolution. Preferably, the absorption volume of each individual hydraulic motor of the fan control circuit is controllable, e.g., via one or more valves are adjustable geometry of the hydraulic motor, so that an independent configuration of the individual hydraulic motors is possible. In contrast to the prior art, this embodiment in accordance with the present disclosure also allows the selective shut-off or shut-down of a fan within the fan circuit.

In a preferred configuration variant of the hydraulic fan control circuit, at least one hydraulic pump is configured as variable displacement pump. By means of the variable displacement pump, the hydraulic flux volume flow within the fan control circuit can be regulated and the prevailing hydraulic pressure within the system can be influenced. This opens up a central possibility for adjusting the respective speed of the interconnected fan drives or hydraulic motors. As in fan drives the required driving torque rises with the speed, the speed of a plurality of fan drives can be varied by regulating the driving torque over the adjustable motors.

Preferably, the variable displacement pump exclusively delivers the hydraulic medium volume flow necessary for the required speed.

In a particularly inexpensive and performance-optimized configuration of the hydraulic fan control circuit according to the present disclosure exactly one hydraulic pump, in particular a variable displacement pump, is provided in the fan control circuit. This one variable displacement pump exclusively delivers the hydraulic medium volume flow necessary for the speed. Thus, a performance-optimized drive is possible in a single-circuit system.

For optimizing the regulation range of the connected hydraulic motors and/or fan drives, a stepless regulation of the fan speed in a range between standstill of the fan and maximum speed is provided. Hence, the economy of the fan control circuit according to the present disclosure can further be optimized and at any time be adapted to the existing environmental and operating conditions.

Expediently, at least two fan drives and/or hydraulic motors are interconnected in the fan control circuit parallel to each other. Connecting the hydraulic motors in parallel effects equal pressure levels at the inlet of the hydraulic motors.

The connection of a pressure regulator to the fan circuit can be expedient.

The fan circuit is designed for the cooling of one or more machine components. Preferably, at least one hydraulic motor with connected fan is provided for cooling the charge air of an internal combustion engine of the machine. What is conceivable is the integration of a hydraulic motor with fan for cooling the water cooling system of the internal combustion engine or for cooling the hydraulic oil.

The present disclosure furthermore is directed to a motor vehicle, a construction machine or a lifting device with a hydraulic fan control circuit in accordance with one of the aforementioned combinations of features. The hydraulic fan control circuit preferably is configured according to one of the aforementioned configuration possibilities, so that a renewed explanation thereof will be omitted at this point.

Further details and advantages of the present disclosure will now be explained in detail with reference to two drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a circuit diagram for the hydraulic fan control circuit of the present disclosure with two fans.

FIG. 2 shows a further circuit diagram for the hydraulic fan control circuit of the present disclosure with three fans.

DETAILED DESCRIPTION

FIG. 1 shows a circuit diagram for the hydraulic fan control circuit in accordance with the present disclosure. FIG. 1 shows a machine 100, which can be a motor vehicle, construction machine, or a lifting device, with the hydraulic fan control circuit 120.

The circuit substantially consists of a single hydraulic variable displacement pump 10 which is designed for one flow direction. The variable displacement pump 10 is connectable or connected with the drive train of a construction machine or a lifting device and is driven by the Diesel unit 122 associated to the machine 100. The variable displacement pump 10 sucks in the hydraulic fluid from the hydraulic tank 60 and delivers the hydraulic medium to the hydraulic motors 20, 30 via the hydraulic lines.

Furthermore, the hydraulic medium delivered is delivered to the hydraulic motors 20, 30 which each are mechanically connected with a fan arrangement in the form of a ventilator 50. Both hydraulic motors 20, 30 can be regulated independently, namely such that their resulting driving torques are adjustable by adjusting the absorption volume of the hydraulic motors 20, 30. Each fan drive may be coupled to a different component requiring cooling airflow. For example, the fan drive including motor 20 is coupled to an air charge of the internal combustion engine 240, and the fan drive including motor 30 is coupled to the cooling liquid of the internal combustion engine 142. Further additional fan drives may be added and may be coupled to a heat exchanger within which the hydraulic oil for the hydraulic system passes to cool the oil. Further alternative task areas are of course conceivable.

The adjustment of the absorption volume of the hydraulic motors 20, 30 is effected in line with keeping the existing hydraulic pressure constant. At the outlet of the hydraulic motors 20, 30 the hydraulic medium flowing through the same is recirculated into the connected hydraulic tanks 60. In one example, a control system 130 is provided including a controller 132 receiving data from a plurality of sensors 134 sensing operating condition. The control includes computer readable media or a system on a chip for carrying out instructions or operations based on the sensed data, including sending control signals to each of the actuators 136 and 138 of the motors 20 and 30, respectively, for independently controlling the absorption volume of the motors to provide different rotation speeds for the fans. In this way, the different cooling needs of the components can be accommodated at the same instance.

Both hydraulic motors 20, 30 are interconnected parallel to each other within the hydraulic system, so that at both hydraulic motors 20, 30 an identical pressure level is obtained.

As in fan drives the required driving torque rises with the speed, the speed of the fan drives 20, 30 can be varied with only one variable displacement pump 10 by adjusting the driving torque, i.e. by adjusting the absorption volume of the motors 20, 30 and by keeping the hydraulic pressure constant. Additionally, where the hydraulic pump 19 is configured as variable displacement pump, by means of the variable displacement pump and actuator 12, the hydraulic flux volume flow within the fan control circuit can be regulated at a first flow by the control system and the prevailing hydraulic pressure within the system can be influenced to a first pressure, while at the same time the control system can adjust the respective speed of the interconnected fan drives or hydraulic motors with respect to one another so that motor 20 operates at a first, lower speed, and motor 30 operates at a second, higher speed, at the same time. Further, the control system may adjust the pump 10 to increase the hydraulic flux volume flow within the fan control circuit to a second, higher flow than the first flow (with the prevailing hydraulic pressure within the system to a second, higher pressure than the first pressure), while at the same time the control system still adjust the respective speeds of the interconnected fan drives or hydraulic motors with respect to one another so that motor 20 operates at a third speed lower than a fourth speed of motor 30, but with both the third and fourth speeds greater than the first and second speeds. Alternatively, still other combinations of speeds may also be used.

The variable displacement pump 10 exclusively delivers the hydraulic volume flow required for the speed to the system. Thus, a performance-optimized drive is possible in a single-circuit system.

Furthermore, the speed of the fans 50 can steplessly be varied in a range between standstill and maximum speed by adjusting the motor absorption volume of the hydraulic motors 20, 30. The circuit hence satisfies the criterion to be able to operate one or more fan drives independent of each other.

FIG. 2 shows the configuration of the hydraulic fan control circuit of the present disclosure with three hydraulic motors 20, 30, 100 for operating one fan mechanism 50 each. While not repeated in FIG. 2, the additional control system and related components requiring cooling are included as well. The configuration provides the parallel connection of three hydraulic motors 20, 30, 100 and substantially corresponds to the configuration of FIG. 1. Identical components of the hydraulic fan control circuit are designated with the same reference numerals.

The two fan control circuits of FIGS. 1 and 2 are suitable for use in large machines, in particular in large mobile machines such as construction machines or lifting devices. The circuit arrangement is integrated in the hydraulic circuit of the machines mostly present anyway and is suitable for a particularly performance-optimized operation of the cooling system. The individual interconnected fans can be controlled independent of each other and therefore allow a particularly economic operation. In addition, individual fan drive units can be shut down, which in the previous configurations known from the prior art has only been possible by integrating additional circuit components. 

1. A hydraulic fan control circuit for a machine, comprising: at least one hydraulic pump and at least one hydraulic motor for driving at least one fan, wherein a hydraulic motor driving torque of at least one hydraulic motor is controllable by adjusting an absorption volume of the at least one hydraulic motor.
 2. The hydraulic fan control circuit according to claim 1, wherein the at least one hydraulic pump is a variable displacement pump and a speed of the one or more fans is adjustable by a hydraulic motor.
 3. The hydraulic fan control circuit according to claim 2, wherein exactly one hydraulic pump is provided in the fan control circuit.
 4. The hydraulic fan control circuit according to claim 3, wherein control of the driving torque and/or of the fan speed is steplessly variable between standstill of the fan and maximum fan speed.
 5. The hydraulic fan control circuit according to claim 4, comprising at least two fans and/or hydraulic motors connected in parallel.
 6. The hydraulic fan control circuit according to claim 5, wherein at least one fan cools an engine charge air.
 7. The hydraulic fan control circuit according to claim 5, wherein at least one fan cools an engine water.
 8. The hydraulic fan control circuit according to claim 5, wherein at least one fan cools hydraulic oil of the machine.
 9. The hydraulic fan control circuit according to claim 1, wherein the hydraulic pump is coupled to a drive train of the machine.
 10. The hydraulic fan control circuit according to claim 9, wherein the drive train drives one or more of a motor vehicle, a construction machine, and a lifting device.
 11. The hydraulic fan control circuit according to claim 1, wherein the pump is a variable displacement pump.
 12. A machine, comprising: a hydraulic fan control circuit including: a variable displacement pump; a first hydraulic motor coupled to a first fan; a second hydraulic motor coupled to a second fan, the second hydraulic motor coupled in the circuit in parallel with the first hydraulic motor, each of the first and second hydraulic motors independently controllable via respectively controlled absorption volumes of the first and second hydraulic motors; and a control system including non-transient, computer-readable medium including instructions which, when executed by a processor, independently adjust fan speed of the first and second fans responsive to conditions, while maintaining the same supply pressure to respective inlets of the first and second hydraulic motors.
 13. The machine of claim 12, wherein the instructions further adjust fan speed from stopped to a maximum speed.
 14. The machine of claim 13, wherein the first fan is coupled to cool a coolant medium of an engine, the engine driving the variable displacement pump; and the second fan coupled to cool oil flowing through the first and second hydraulic motors.
 15. A hydraulic fan control circuit for a machine, comprising: a first hydraulic pump providing pressure to a first hydraulic motor driving a first fan, the pump further providing pressure to a second hydraulic motor driving a second fan, wherein a hydraulic motor driving torque of each of the first and second hydraulic motors is independently controllable by adjusting respective absorption volumes of the first and second hydraulic motor, while maintaining the same pressure provided to the first and second hydraulic motors. 